The proposed three year study seeks to understand the nature of drug use and HIV risk behaviors among Asian ethnic groups. San Francisco, an AIDS epicenter with among the highest annual rates of AIDS cases, also has one of the highest concentrations of Asian and Pacific Islanders in the nation (n=210,876). Preliminary data suggest that recent Asian immigrants may primarily use drugs in ethnically homogenous drug use networks. The nature of these networks and behaviors related to cultural factors may be contributing to HIV transmission among these groups. The aims of the proposed study are: (1) to identify the patterns of drug use among three Asian ethnic groups; (2) to identify the pattern and prevalence of HIV infection and risk behaviors among thee Asian drug users; and (3) to test hypothesis that describe relationships among conceptually related sets of demographic, psychological, and cultural variables in order to develop a model useful in the prediction of HIV risk behaviors among Asian drug users. In close coordination with an existing service program, this street-based study will obtain individual interviews from adult Chinese, Filipino, and Vietnamese immigrants and native-born residents of the United States. A total of 300 interviews with crack/cocaine and/or injection drug users who are not in treatment will be completed. The study has three specific stages: (1) Initial mapping and qualitative observations and interviews; (2) Piloting of instruments and procedures; and (3) Structured interviews. The first stage will obtain in depth information of drug use and HIV risk behaviors in these populations through observations and qualitative interviews of at least 30 drug users per ethnic group. Based on the data gathered in the first stage, instruments and procedures will be refined and piloted during the second stage. The final stage of the study consists of 90-minute structured interviews and HIV antibody testing. Through the preceding stages, a modified targeted sampling procedure to reach at least 100 drug users in each ethnic group, 50% of whom will be women and immigrants, will have been developed. Interviews will be conducted in English, Chinese, Tagalog, and Vietnamese by bilingual interviewers at field sites. The measurements include sociodemographic variables including immigrant status and network characteristics, HIV related health cognitions and perceptions (e.g., outcome expectancies and perceived group norms toward HIV protective behaviors, and perceived susceptibility and knowledge about AIDS), cultural variables such as interdependence, and HIV risk behaviors. The hypothesis describing the relationships among the elements of the constructs will be tested by logistic and multiple regressions. A model to predict specific HIV risk behaviors will be tested by path analysis or LISREL. The study's significance relates to the documentation of methodology and instrumentation for the study of such hidden populations, the determination of the usefulness of existing HIV risk reduction models with Asian drug users, and the determination of the usefulness of distinguishing cultural and social constructs among immigrant drug users to understand and predict HIV risk behavior.